Illuminating appliance.



W. A. DOREY.

ILLUMINATING APPLIANCE.

APPLICATION FILED AUGJ. 1917.

l w iw, Emma Mar. 19, 1918 2 SHEETS-SHEET 2.

A TTOR/V E Y w. A. DOREY.

ILLUMINATING APPLIANCE.

APPLICATION FILED AUGJ. I9I7.

1,259,498. Patented Mar. 19, 1918.

2 SHEETS-SHEET l.

H/d/MW, dw aw A TTOfl/VEV WILLIAM A. DOEEY, 0F NEWARK, OHIO, ASSIG-NOBT0 HOLOPHANE GLASS COMPANY, me, OF NEW YORK, N. Y., A CORPORATION OF NEWJERSEY.

ILLUMINATING AIPPLIANCE.

Specification of Letters Batent.

Patented Mar. 19, 191%..

To all whom it may concern:

Be it known that 1, WILLIAM A. Donny, a citizen of the United States,residing at Newark, in the county of Licking, State of Ohio, haveinvented certain new and useful Improvements in Illuminating Appliances,of which the following is a specification.

The object of my invention is to construct an illuminating appliancewhich shall produce eflicient illumination on the working plane and atthe same time reduce the glare to a minimum. It is accomplished byreducing the amount of light emitted in certain zones, and preventingundiflused light from being emitted in said zones. Eficient combinationsof this sort are formed in the known forms of open mouth prismaticreflector, but a portion of the light striking the surface of such areflector is transmitted giving the appearance of a bright spot on theoutside of the reflector, which is in line with the light source, andthe eye of the observer. Under certain conditions where the reflector isclose to the observer or mounted low, this bright spot may becometroublesome. In the present invention, the reflector portion stops atsuch an angle that such bright spots are not visible at any ordinarypoint of view. At this point, the transmitting part of the appliancebegins and extends to an angle equivalent to that of the ordinary formof rismatic reflector. With the concentrated light sources, now in use,the refracting construction used on this transmitting portion can bemade so as to permit little or no undiflused light to lee-emitted attroublesome angles.

Figure 1 is an elevation of a shade-reflector made according to myinvention, with a portion cut away to show the vertical section. Figs. 2and 3 are vertical sections of further modifications of my invention.

The device is compound; one portion, generally'the upper being formed asa reflector, and the lower portion as a transmitting shade. The deviceis shown of crystal glass, but tinted, colored, acid etched, or sandblasted glass can be used; or the reflector portion may be made ofopaque material.

In the preferred form, the reflector is formed of crystal glass whichhas on its outer surface radial double reflecting prisms adapted toreflect li ht rays from the source within, through an out of the openmouth of the appliance. Between the reflector and the refracting portionis a band-like portion joining the reflector to the refractor. The onlymechanical reason for using this is to secure good manufacturingconditions. The refractor portion consists of a band of refractingprisms, the lower portion of this band being of smaller diameter thanthe upper fpart thereof. In fact, the opening of the re 'racting portionneed only be of such width as to permit the removal of the lamp.

The reflector is designed so that practically no light rays from thesource are reflected from it to the inner surface of the transmittingshade portion, as such light would be more scattered than light raysdirectly incident on the shade portion, and would not pass out in suchangles as to pro duce the desired definite cutofli' or diminution abovethe angle of maximum light intensity. The contour of the upper reflectoris substantiallv elliptical, that is, of such outline that if the lightsource is placed in one focus the reflected rays will tend to passthrough the other focus. In actual design, in order to get difference indistribution, we are only limited to the requirements of getting thereflected rays through the open mouth. As this is of somewhat restrictedarea, however, the reflector can always be considered as a combinationof elliptical and parabolic constructions, if not as a simple ellipse.

The mouth of the transmittin portion is of such size that the reflectedlig t from the reflector portion may be made to pass through it at suchangles as to give desirable distribution without loss by impinging onthe transmitting portion. The shape of the transmitting portion and itsrelation to the light source are such that the light rays striking itare refracted efliciently into the useful zones.

In the figures, B is the upper reflector portion having on its outersurface double reflecting prisms. The neck portion A in each case is ofconventional form. G is the light source of which E is the center andtaken as the light source for the purpose of showing the action oftypical light rays.

This point E is taken as one focus of the various ellipses and as thefocus of the pa rabola forming the contour of the upper reflector part.The lower refractin portion D of the appliance is shown as wel ed to thereflector by means of band C, which has reflecting prisms upon it.Portion D has an open mouth F large enough to permit passage of the lampG, and has horizontal refracting prisms upon its outer, surface. Thelight rays incident from the light source on the reflector 13, abovepoint 2, are for all practical purposes negligible.

In the modification shown in Fig. 1, the contour of the reflector from 2to 5 and from 7 to 10 is elliptical, while that from 5 to 7 isparabolic. Rays from 2 to 5 pass through point 18, placed close enoughto the edge of the mouth part to ermit a Wide distribution of the lightan yet not close enough to cause the rays from the extreme edge of thesourceto be reflected on the inner surface of the transmitting portion.The ray point 5 coincides with the axis of the ellipse. Point 18 forms asecondary light focus for all rays incident on the elliptical portion 2to 5 of the reflector. Rays incident on points from 7 to 10 pass throughpoint 19. This point is so placed that practically all light reflectedfrom extreme portions of the light source will miss the adjacent side ofthe transmitting portion. This point 19 forms the secondary focus ofrays incident on the second elliptical portion of the reflector. Portion5 to 7 on'the reflector is parabolic in contour and. all the rays fromthe source E reflected by it will be parallel to rays 4: and '8. Therefracting transmitting part extends from about -90 degrees With thevertical axis to about '55 degrees with the vertical axis and isdesigned to emit through its open month all direct light from the sourceemitted at angles less than 55 degrees to 60 degrees. The refractorportion is here shown as concave and provided with horizontal refractingprisms which inthis case depress the major portion of the light strikingthe in her surface to about 45 degrees and permit very little light topass out above an angle of 60 degrees. Typical light ray 16 from thelight source is incident on such refracting prisms, and refracted andtransmitted in direction 17 as shown. Light rays 12 incident on theconnecting band at point 13 are reflected and transmitted in typicallight rays 14 and15.

Fig. 2 is the vertical cross section of a modification in which thecontour of the reflector from 20 to 21 andfrom 22 to 23 is elliptical,While that from 21 to 22 is parabolic. The light rays incident from thelight source on the reflector B, above point 20, are for all practicalpurposes neg-v ligible. Rays from 20 to 21 pass through point 24, soplaced that the reflected rays are at angles from perpendicular to 33degrees with the perpendicular. Point 24 forms a secondary light focusfor all rays incident on the elliptical portion 20 to 21 of thereflector. Rays incident on points from 22 to 23 pass through point 25.This point is so placed that practically all light reflected fromextreme portions of the light source will pass out through the openmouth at angles less than degrees and very little of the light willstrike the adjacent side of the transmitting portion. This point formsthe secondary focus of rays incident on the second elliptical portion ofthe reflector. Portion 21 to 22 on the reflector is parabolic in contourand all the rays from the source E reflected by it will be parallel torays 26 and 27.

The refracting transmitting part extends from. about 85 degrees With thevertical axis to about degrees With the vertical axis and is designed toemit through its open mouth all direct light from the sources emitted atangles less than 55 degrees to 60 degrees. The refractor portion is hereshown as concave and provided with horizontal refracting prisms which inthis case depress the major portion of the light striking the innersurface to about 33 degrees .and permit very little light to pass outabove an angle of 60 degrees. Typical .light ray 28 from the lightsource is ncident on such refracting prisms, and refracted andtransmitted in direction 29 as shown.

Light rays 30 incident on the connecting band at point 31 are refractedand transmitted in typical light rays 32 and 33.

In Fig. 3, a vertical cross section of a further modification of myinvention is shown. In this modification the light rays incident fromthe light source on the reflector B, above point 34, are for allpractical purposes negligible. Rays from 34 to 35 pass through point 37,placed at the edge of the mouth part. In this case rays from theextremeedge of the light source are reflected on the opposite side of thetransmitting portion because the prisms at the lower edge are so shallowthat they will not direct this light disadvantageously and a wide angleof maximum intensity is desired Without increase in' the size of themouth F. Point 37 forms a secondary light focus for all rays incident onthe elliptical portion 34 to 35 of the reflector. Portion 35 to 36 onthe reflector is parabolic in contour and all the rays from the source Ereflected by it will be parallel to rays 38 to 39.

The refracting transmitting part extends from about 85 degrees with thevertical axis to about 55 degrees with the vertical axis and is designedto emit through its open mouth all direct light from the sources emittedat angles less than 55 degrees to 60 degrees. The refractor portion ishere shown as concave and provided With hori zontal refracting prismswhich in this case depress the major portion of the light striking theinner surface to about 55 degrees and permit very little light to passout above an angle of 60 degrees. Typical light ray 40 from the lightsource is incident on such refracting prisms, and refracted andtransmitted in direction41 as shown. Light rays 42 incident on theconnecting band at point 45 are refracted and transmitted in typicallight rays 43 and 44.

Great variety of distribution is obtainable by this invention. Figs. 1,2 and 3 show three distinct types in which variations are produced bydlflerent ellipsoidal combinations in the reflector together withdifierence of curvature of the transmittin part. For instance, in Fig. 1a broad distri ution is given inv which an area is lighted, the diameterof which is twice the distance of the light source above the planelighted. The area of distribution of Fig. 2is smaller but moreconcentrated, being 14 times the distance of the light'source above theplane lighted. The broadest area of distribution is obtained by themodification shown in Fig. 3, in which the diameter of the area lightedis 2% times the distance of the light source above the plane lighted.

The appliance 1s shown in pendent position but it can be used upright orpendent; any light source can be used but accuracy of position isnecessary to secure good results.

Having described my invention, what I claim is:

1. An illuminating appliance consisting of an upper reflector, a lowerlight transmitting shade, having an open mouth the reflector beingsubstantially ellipsoidal in contour and adapted to throw the majorityof light rays incident on its surface directly through and out of theopen mouth and the shade transmitting and directing incident light raysat angles to roduce a relatively sudden diminution in light intensityabove the angle of maximum light intensity.

2. An illuminating appliance consisting of a light transmitting shadehaving an open mouth and an upper reflector substantially ellipsoidal incontour and provided on its outer surface with radial reflecting prismsadapted to throw the majority of light rays incident on its surfacedirectly through and out of the open mouth and the shade which has uponits surface prisms adapted to transmit and direct incident light rays atangles to produce a relatively sudden diminution in light intensityabove the angle of maximum light intensity.

3. An illuminating appliance consisting of a light source and surroundinthe same, a reflector and an open mouthed light transmitting shade, thereflector being uppermost and having its rim substantially on a linewith a lower edge of the light source and being adapted to throw themajority of light rays incident on its surface directly throu h and outof the open mouth of the shade, which shade transmits and directs lightrays incident thereon at angles to produce a relatively suddendiminution in light intensity above the angle of maximum lightintensity.

4. An illuminating appliance consisting of a light source andsurrounding the same, a glass reflector and anopen mouthed lighttransmitting shade, the reflector being uppermost and having its lowerrim substantially On a line with the lower edge of the light source andbeing rovided with reflecting prisms adapted to t row the majority oflight rays incident on its surface directly through and out of the openmouth of the shade, which shade transmits and directs light raysincident thereon at angles to produce a relatively sudden diminution inlight intensity above the angle of maximum light intensity.

5. An illuminating appliance consisting of a light source and surroundinthe same, an upper reflector, and a lower ight transmitting open mouthedshade, the reflector being substantially ellipsoidal in contour andhaving its lower rim substantially on a line with the lower edge of thelight source and being provided on its outer surface with radialreflecting prisms adapted to throw the majority of light rays incidenton its surface directly through and out of the open WILLIAM A. DOREY.

